A Highly Sensitive Mercury Ion Sensor Based on Solid-Liquid Contact Electrification

Abstract

In recent years, triboelectric nanogenerators (TENGs) are proved to be as the prime backbone for developing a self-powered sensing system. However, solid-solid contact electrification based nanogenerators suffer mostly due to inefficient contact which poses a major bottleneck for the development of long term durable and stable nanosensors. In this regard, we have reported a strategic methodology to develop a highly sensitive mercury ion sensor based on solid-liquid contact electrification, which has prime importance for the self-powered monitoring of mercury ion due to its high health risk and environmental pollution toxicity. In this work, 3-mercaptopropionic acid (MPA) capped Au nanoparticles (NPs) are employed as the solid friction layer as well as the recognition element for mercury ion detection. In addition, volatile organic solvent acetone is utilized as the contact liquid instead of water. The developed nanosensor exhibits long term stability and contact frequency independent sensing performance compared to previously reported solid-solid triboelectric nanosensors (TENS) for mercury ion detection. The large binding affinity of Hg2+ and the carboxylic groups results in the increase of transferred charges and enhanced surface potential. It is interesting to observe that the work function reduces after the binding of Hg2+ ions onto MPA molecules, which is also favorable for electron transfer during the contact electrification process. The developed nanosensor can provide a wide linear detection range from 10 nM to 1 μM as well as a low detection limit of 10 nM. As a whole, this work demonstrates a novel paradigm for designing a rapid, low-cost, and portable self-powered sensing system for real time highly selective monitoring of mercury ion from complex environmental samples.